This invention relates to apparatus for treating a grass playing field and, in particular, to apparatus for treating the turf of a grass playing field by selectively moving air in either direction through the soil profile of the playing field.
The term turf, as herein used, refers to the upper layer of earth which typically supports vegetation which, in this case, is preferably grass. The term subsoil or subsoil profile as herein used, refers to one or more prepared layers situated beneath the playing field that are designed to promote the health of the grass turf. The subsoil profile may contain one or more soil layers situated immediately below the turf that are prepared from mostly natural organic matter or mixtures thereof designed to feed or otherwise sustain the grass rootstock. Below the soil layers may be a choker layer which is predominantly sand and finally a gravel bed capable of distributing air.
Many grasses, and in particular, those used on golf course greens, are temperature sensitive and thus tend to become dormant or die off when exposed to either high or low ambient temperatures. Many golf course greens in southern climates contain bent grasses that are native to more northern climates. These grasses, unless somehow protected, die off in the summer, thus making play difficult during a time when it is most desirable to use the course. Heretofore, large fans have been used with some success to move cooling air across the surface of the green during periods of high temperatures. Overwatering and syringing of the greens has also been employed with success to cool the grass of a putting green. However, these methods have proven to be expensive, time consuming and adversely effect play on the course. Little has been done, on the other hand, to protect the sensitive golf course grasses during cold spells.
As explained in greater detail in co-pending U.S. application Ser. No. 08/177,441 filed Jan. 5, 1994, now U.S. Pat. No. 5,433,759, an underground system has been devised for both heating and cooling grass on a golf course green using the available air and ground as sources of energy. Either the suction side or the discharge side of a blower is selectively attached to a perforated piping system laid in a gravel bed beneath the soil of the green. Depending on the relative air and ground temperatures, air is either pushed upwardly or pulled downwardly through the soil profile to achieve the desired cooling or heating of the turf. It is important, however, to limit the amount of moisture that is carried by the air stream as it passes through the system for a number of reasons. When the blower is operating in a suction mode, excessive water found in the subsoil profile can be pulled into the rotating stages of the machine where it can produce excessive wear and corrosion of the rotor, the machine, and stator parts. If the green has been treated with fertilizer or other chemicals, the corrosion process is greatly accelerated, thus leading to early machine failure. In the event the humidity content of air drawn in the blower during the pumping mode is high, the air flow passing upwardly through the soil profile will leave behind a good deal of water. This, in turn, can adversely effect moisture content in the subsoil profile of the playing field.